A power conversion device normally includes an inverter circuit that generates AC power from DC power provided thereto and a control circuit via which the inverter circuit is controlled. Miniaturization of such power conversion devices has been eagerly pursued in recent years. In application areas such as hybrid vehicles and electric vehicles, in particular, the space taken up by a power conversion device in an engine compartment outside the cabin needs to be minimized and thus, further effort for miniaturization must be made so as to improve the installation flexibility of the device in the vehicles.
In addition, there is a distinct tendency whereby the motor utilized as a drive source is engaged in operation over extended periods of time and under extended operating conditions (i.e., higher output torque conditions), and thus, even greater current and higher voltage need to be assured through power conversion. Against this backdrop, momentary spiking of voltage (surge voltage) tends to occur as the power semiconductor elements configuring the inverter circuit are engaged in switching operation. The surge voltage occurring in such an instance manifests as the product of the total of the values of inductance at the bus bars in the capacitor module and the power semiconductor modules and the extent of change occurring in the current during the switching operation. Configuring a capacitor module with a bus bar structure assuring a low inductance value is considered an effective means for inhibiting surge current and thus ensuring that the power semiconductor elements are driven within a safe operation range.
Patent literature 1 discloses an example of a system through which lower inductance is achieved at bus bars.
However, the inductance at the bus bars needs to be further lowered in order to allow power conversion devices to achieve an even greater current and an even higher voltage.